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A new study shows that people with early stage Parkinson’s disease (PD) have sleep disturbances, loss of smell and other easily measured symptoms of disease more often than healthy adults. The researchers suggest that testing for such nonmotor symptoms, when combined with the standard assessments of movement symptoms, can help doctors diagnose PD more accurately. The research appears in the August 20 online edition of Neurology.

Doctors have long diagnosed Parkinson’s disease by observing symptoms related to movement, such as tremor, slowness and balance difficulties. In recent years, doctors and people with PD alike have become more aware of other PD symptoms not related to movement—for example, constipation, mood changes and certain sleep problems. Nonmotor symptoms can appear early in the course of PD, even before movement difficulties develop.

Led by Brit Mollenhauer, M.D., researchers at the Center of Parkinsonism and Movement Disorders in Kessel, Germany, the country’s largest hospital for parkinsonism, set out to systematically define these early nonmotor symptoms. The scientists enrolled 159 study participants recently diagnosed with Parkinson’s disease who had not started treated with levodopa (Sinemet®), as well as 110 healthy participants of similar age and education. Study participants answered questionnaires to assess digestive problems, pain, sleep, mood and other potential PD symptoms. They also had standard blood tests, took tests of smell sensitivity, underwent a laboratory sleep study and had an ultrasound scan of the brain known as transcranial sonography (TCS).

Results

Responses to the survey indicated that people with early stage Parkinson’s disease and healthy participants had very different experiences in terms of nonmotor signs and symptoms.

People with Parkinson’s generally had higher heart rates than healthy participants.

Men with Parkinson’s had lower cholesterol levels.

In smell tests, people with Parkinson’s disease were less able to detect and identify odors.

In sleep studies, 51 percent of people with PD had abnormal movement during REM sleep, the dreaming phase, compared with 15 percent of healthy individuals.

The researchers found no difference between the two groups in levels of urate in the blood, a natural antioxidant that has been associated with slower progression of PD in other studies.

The brain scan did not reveal differences between people with early stage Parkinson’s and healthy participants.

What Does It Mean?

In the early stages, PD can be difficult to distinguish from other disorders that cause similar movement difficulties. As of now, there is no blood test, scan or other measurement that can diagnose PD definitively. The study authors suggest that the current practice of diagnosing PD – based entirely on the basis of movement symptoms – misses many symptoms and signs that are evident in early stage PD and could aid in earlier diagnosis.

If larger studies produce similar results to those reported here, questionnaires could be used as screening tools to hone in on a PD diagnosis before carrying out more expensive evaluations. Furthermore, a range of tests for nonmotor symptoms could improve the accuracy of diagnosing PD. The researchers plan follow-up studies with this group of participants to investigate whether such tests are valuable for measuring or predicting disease progression.